1. Field of the Invention
This invention relates generally to a semiconductor integrated circuit such as a nonvolatile semiconductor memory, and more particularly to a nonvolatile memory cell from which data can be read out at a high speed and a nonvolatile semiconductor memory device having the same.
2. Description of the Related Art Nonvolatile semiconductor memory devices have been widely used, which comprise a multilayer-gate type nonvolatile memory cell transistor having a floating gate and a control gate. The nonvolatile semiconductor memory devices include an EEPROM (electrically erasable and programmable read only memory) and an EPROM (erasable and programmable read only memory).
The conventional multilayer-gate type nonvolatile memory cell transistor having a floating gate and a control gate has a threshold voltage higher than a normal MOS transistor. Hence, the current driving capacity thereof is low and data cannot be easily read out at high speed.